Last month I had the opportunity to moderate a plenary session on “Climate Proofing the World’s Megacities: Building Adaptable and Livable Cities” at the C40 Cities Climate Leadership Group’s bi-annual summit.

The event brought together over 300 leaders from more than 60 global cities working together to reduce greenhouse gas emissions and climate risks, including the Mayors of Addis Ababa, Philadelphia, Rotterdam, and Venice, who participated in my panel. (The Mayor of Rome was scheduled to attend, but forced to cancel his trip due to extreme flooding in his home city).

Together the 63 C40 Cities represent 600 million people worldwide, 5% of global greenhouse gas emissions and 21% of GDP.

The cities on my panel offer a terrific snapshot of the types of challenges and solutions being used in cities to address water risks. The population of Addis Ababa, which has doubled its built environment in the past 40 years, is increasing by 3.8% a year.

This presents tremendous challenges to a city that already has a 28% gap in available water supply and demand, has limited sewage infrastructure, and has experienced 25 severe flood events in the past 40 years.

Philadelphia has launched one of the most ambitious green infrastructure programs in the U.S. to better manage its stromwater and reduce combined sewer overflows through the construction of distributed green spaces and stormwater BMPs—an effort that the Conservancy has been involved in through our work in the NatLab consortium.

Rotterdam and Venice both face significant coastal flood risks from sea level rise and, in the case of Venice, subsidence, and are undertaking multi-billion projects to increase their resilience.

In response to the risks that they are facing, C40 Cities are taking concrete actions. A new report released by C40 at the summit, found that C40 Cities have more than 8,000 climate actions currently underway.

In 2013, C40 Cities only reported undertaking 590 water actions. While this is a 53% increase from 2011, when the last survey was completed, it remains one of the least active areas in the survey.

However, this likely underestimates water activities, as many water-related activities were categorized in other areas. For instance, while most adaptation activities are focused on coastal and surface flooding, activities to address water scarcity are increasing. 82 adaptation actions (8% of 1,024 total reported adaptation actions) are focused on water supply risks.

While actions related to water are not yet a top issue for C40 cities, this is likely to change as the membership of C40 expands to include more cities from Africa (Nairobi, Dar es Salaam, and Cape Town announced that they were joining C40 at the Johannesburg summit). African cities reported the greatest focus on future water actions in the C40 report.

Leading these actions is tree plantings, with 84% of reporting cities undertaking tree planting programs and 80% delivering large-scale open space initiatives.

This growing activity around water and natural infrastructure represents a tremendous opportunity for The Nature Conservancy to share our knowledge on water management and the role of nature and sound resource management policies in mitigating water risks—a key focus of the Securing Water program.

Partnering with cities and organizations such as C40, which offer a single point of contact to reach multiple cities, will be critical to accelerate the pace of change we seek and to ensure that the new urban infrastructure being built and land use decisions are being made today, meet the water needs of people and nature.

Opinions expressed on Conservancy Talk and in any corresponding comments are the personal opinions of the original authors and do not necessarily reflect the views of the Conservancy.